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Regents Biology Proteins
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Regents Biology 2006-2007 Proteins: Multipurpose molecules
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Regents Biology Proteins insulin collagen (skin) hemoglobin Examples muscle fingernails, claws skin hair enzymes example: pepsin hormones example: insulin
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Regents Biology Proteins Function: many, many functions hormones insulin movement muscle immune system protect against germs enzymes help chemical reactions
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Regents Biology Proteins Building block = amino acid amino acid – amino acid – amino acid – amino acid – —N——N— H H H | —C— | C—OH || O variable group amino acids 20 different amino acids
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Regents Biology Amino acid chains Proteins amino acids chained into a polymer Each amino acid is different some “like” water & dissolve in it some “fear” water & separate from it
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Regents Biology Water-fearing amino acids Hydrophobic “water fearing” amino acids try to get away from water in cell the protein folds
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Regents Biology Water-loving amino acids Hydrophillic “water loving” amino acids try to stay in water in cell the protein folds
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Regents Biology pepsin 3-D protein structure collagen Proteins fold & twist into 3-D shape hemoglobin growth hormone
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Regents Biology Proteins (Polypeptides) Four levels of protein structure: A.Primary Structure B.Secondary Structure C.Tertiary Structure D.Quaternary Structure
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Regents Biology Primary Structure peptide bonds (straight chains) Amino acids bonded together by peptide bonds (straight chains) aa1aa2aa3aa4aa5aa6 Peptide Bonds Amino Acids (aa)
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Regents Biology Secondary Structure primary structurecoilspleats hydrogen bonds 3-dimensional folding arrangement of a primary structure into coils and pleats held together by hydrogen bonds. Two examples: Alpha Helix Beta Pleated Sheet Hydrogen Bonds
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Regents Biology Tertiary Structure Secondary structuresbent foldedmore complex 3-D arrangement Secondary structures bent and folded into a more complex 3-D arrangement of linked polypeptides Bonds: H-bonds, ionic, disulfide bridges (S-S) “subunit”. Call a “subunit”. Alpha Helix Beta Pleated Sheet
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Regents Biology Quaternary Structure Composed of 2 or more “subunits” Globular in shape Form in Aqueous environments enzymes (hemoglobin) Example: enzymes (hemoglobin) subunits
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Regents Biology Its shape that matters! Proteins do their jobs, because of their shape Unfolding a protein destroys its shape wrong shape = can’t do its job unfolding proteins = “denature” temperature pH (acidity) folded unfolded “denatured”
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